In petroleum catalytic cracking processes, spent or equilibrium catalyst particles are burned as part of a coke removal process and the resulting stack gases are subjected to caustic scrubbing prior to their emission into the atmosphere. The particles and fluids obtained from the caustic scrubbing process typically have been deposited in a settling pond, with the particles periodically being removed from the pond and disposed of by being blended into surficial soils or buried in land fills. Increasingly, however, the various agencies responsible for controlling the disposal of industrial solid waste are prohibiting these disposal practices. As a result, other disposal methods must be considered.
One way to dispose of such spent petroleum cracking catalyst particles is to use them as an ingredient in other compositions. This would avoid costly disposal practices and in addition give the particles a commerical value of their own. This has already been done to an extent in the use of spent petroleum cracking catalyst particles as a filler in concrete. The amount of such filler which can be used in a concrete mix is relatively small, however, since cement is the major ingredient in the concrete and since larger size aggregates must also be included.
A preferred end use for spent petroleum cracking catalyst particles would be one in which large quantities of the particles are required, preferably as the main ingredient of a composition which itself is required to be used in large quantities. A composition useful in the construction industry, for example, would be desirable from the standpoint of the great quantities of particles which would be required. Such an end use would appear highly unlikely, however, since the catalyst particles are so much smaller than the particles which are conventionally used. For example, the bulk of the limestone or gravel used in the base course of a roadway is typically 3/8 inch to 3/4 inch in size, whereas the catalyst particles under discussion are in the range of only 1 to 200 microns in size. This great disparity in size is brought into perspective when noting that the upper end of the range of 200 microns corresponds to about 1/128 of an inch. The particles of spent petroleum cracking catalyst are thus more powderlike in nature in contrast to the much larger particles used in constructing a road base course. The same is true of the material normally employed as fill in the construction of a barrier such as a levee or dike. Powderlike material normally would not be suitable in either type of construction, and if used in a levee fill would be far too permeable.